Issue 6433 - Use generators in getURLsFromElement

include.preload.js

Index: include.preload.js
===================================================================
--- a/include.preload.js
+++ b/include.preload.js
@@ -30,21 +30,24 @@
   ["audio", "MEDIA"],
   ["video", "MEDIA"],
   ["frame", "SUBDOCUMENT"],
   ["iframe", "SUBDOCUMENT"],
   ["object", "OBJECT"],
   ["embed", "OBJECT"]
 ]);
 
-function getURLsFromObjectElement(element)
+function* getURLsFromObjectElement(element)
 {
   let url = element.getAttribute("data");
   if (url)
-    return [url];
+  {
+    yield url;
+    return;
+  }
 
   for (let child of element.children)
   {
     if (child.localName != "param")
       continue;
 
     let name = child.getAttribute("name");
     if (name != "movie" &&  // Adobe Flash
@@ -52,85 +55,58 @@
         name != "src" &&    // Real Media + Quicktime
         name != "FileName") // Windows Media
       continue;
 
     let value = child.getAttribute("value");
     if (!value)
       continue;
 
-    return [value];
+    yield value;
+    return;
   }
-
-  return [];
 }
 
-function getURLsFromAttributes(element)
+function* getURLsFromAttributes({src = "", srcset = ""})
 {
-  let urls = [];
-
-  if (element.src)
-    urls.push(element.src);
+  yield src;
 
-  if (element.srcset)
-  {
-    for (let candidate of element.srcset.split(","))
-    {
-      let url = candidate.trim().replace(/\s+\S+$/, "");
-      if (url)
-        urls.push(url);
-    }
-  }
-
-  return urls;
+  for (let candidate of srcset.split(","))
+    yield candidate.trim().replace(/\s+\S+$/, "");
 }
 
-function getURLsFromMediaElement(element)
+function* getURLsFromMediaElement(element)
 {
-  let urls = getURLsFromAttributes(element);
+  yield* getURLsFromAttributes(element);
 
   for (let child of element.children)
   {
     if (child.localName == "source" || child.localName == "track")
-      urls.push(...getURLsFromAttributes(child));
+      yield* getURLsFromAttributes(child);
   }
 
-  if (element.poster)
-    urls.push(element.poster);
-
-  return urls;
+  yield element.poster;
 }
 
 function getURLsFromElement(element)
 {
-  let urls;
-  switch (element.localName)
-  {
-    case "object":
-      urls = getURLsFromObjectElement(element);
-      break;
+  let urls = null;
 
-    case "video":
-    case "audio":
-    case "picture":
-      urls = getURLsFromMediaElement(element);
-      break;
+  let {localName} = element;
 
-    default:
-      urls = getURLsFromAttributes(element);
-      break;
-  }
+  if (localName == "object")
+    urls = getURLsFromObjectElement(element);
+  else if (["video", "audio", "picture"].includes(localName))
+    urls = getURLsFromMediaElement(element);
+  else
+    urls = getURLsFromAttributes(element);
 
-  for (let i = 0; i < urls.length; i++)
-  {
-    if (/^(?!https?:)[\w-]+:/i.test(urls[i]))
-      urls.splice(i--, 1);
-  }
-
-  return urls;
+  return Array.from(urls).filter(
+    url => url && !/^(?!https?:)[\w-]+:/i.test(url)
+  );
 }
 
 function hideElement(element)
 {
   function doHide()
   {
     let propertyName = "display";
     let propertyValue = "none";